The Muse holds what looks like a ball and a stick. They are in fact an astronomical globe and a radius – a drawing rod – showing us that this is Urania, the Muse of astronomy.
The statue’s body looks much bigger than the other Muses in Gustav III's Museum of Antiquities. One could argue this fits Urania as she is the Muse who represents the firmament - the skies above the earth. However, the real reason is that this statue originally belonged to another series of sculptures with different body types.